Rankings, running totals and more.
✍️ 3 exercises + code challenge in this lessonWindow functions calculate across a set of rows related to the current row, without collapsing them into one row like GROUP BY does.
function() OVER (PARTITION BY ... ORDER BY ...)
ROW_NUMBER(), RANK(), DENSE_RANK(): numbering and ranking.SUM() OVER (...): running totals.LAG() / LEAD(): values from the previous / next row.Mastering SQL Window Functions helps you write clean and reliable SQL code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
SELECT ProductName, Category, Price,
RANK() OVER (PARTITION BY Category ORDER BY Price DESC) AS RankInCategory
FROM Products;
SELECT OrderID, OrderDate,
COUNT(*) OVER (ORDER BY OrderDate) AS RunningOrderCount,
LAG(OrderDate) OVER (ORDER BY OrderDate) AS PreviousOrder
FROM Orders;Check what you learned in “SQL Window Functions”.
Number rows by price, highest first.
ROW_NUMBER() (ORDER BY Price DESC)
How are window functions different from GROUP BY?
Select ProductName and RANK() OVER (ORDER BY Price DESC) AS PriceRank for the 3 most expensive products.
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